Hydraulic press



Jan. 29, 1929.

. 1,700,363 L. A. BARRETT ET AL HYDRAULIC PRESS Filed Dec. 51, 1925 24 5 n H 25 b q i 37 Wgfig 7 INVENTORS 1 5 ZAWPEMTA Bnmsrr 7 BY Jo /y Pi k/P25.

ATTORNEY Patented Jan. 29, 1929.

UNITED sTArEs PATENT OFFICE.

LAWRENCE A. BARRETT AND JOHN P. reams, or MILWAUKEE, WISCONSIN, AS-

SIGNQRS ro THE OILGEAR COMPANY, or MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

HYDRAULIC PRESS.

Application filed December 31, 1925. Serial No. 78,513.

This invention relates to heavy duty presses, and more particularly to hydraulic drives therefor.

Very little effort is required to operate the ram of an ordinary heavy duty press toward and from the work, as compared with that required to actually apply heavy pressures to the work. When the ram is operated by liquid delivered from an accumulator, or other constant pressure source, there is, therefore, a considerable loss of energy during the advance of the ram toward the work, due to the necessarily intensive throttling of the driving liquid to avoid excessive ram speeds. When operated by liquid delivered from a pump, the advance of the ram is ordinarily very slow, because of the large volume of liquid demanded by the ram.

One object of the present invention is the provision .of a pump operated hydraulic press involving a novel combination of parts for effecting a quick regulated advance of the ram toward the work, and thereafter operable to apply the desired heavy pressures to the work. In the press hereinafter described this is accomplished by the. use of an auxiliary iston and cylinder which receives drivingliquid from the pump for effecting quick movement of the ram, the heavy pressures being obtainable by exposing the ram to the discharge of the pump after the quick advance of the ram.

Another object of the present invention is the provision of means for automatically effecting the above operating sequence.

Another object is the provision of pressure responsive means for automatically connecting the power cylinder of the ram to the pump after the quick advance of the ram.

Other objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

In the drawings Figure 1 is a sectional View of a hydraulic press embodying the novel features of the present invention.

'Fig. 2 is a sectional view of the control valve shown in Figure 1, and illustrating two extreme positions thereof.

Fig. 3 is a sectional view of an automatic valve shown in Figure 1, illustrating a second position thereof.

The press selected for illustration includes tically from the power cylinder 10. A piston 16, closely fitted for reciprocation in the cylinder 15, is directly connected, through a rod 16, with the ram 13. Pipes 17 and 18 lead from the upper and lower ends, respectively of the cylinder 15 to an appropriate control valve 19, which is supplied with driving liquid from a pump 20.

The pump shown is fully described in the copending application of Walter Ferris, Serial No. 701,356, filed March 24, 1924. It is a smooth delivery, variable displacement pump that receives liquid from a pipe 21 and discharges liquid into a pipe 22 at a rate proportional to pump displacement." The valve shown is also described in said application. It comprises a piston having three heads 23, 24 and 25, connected by reduced portions26 and 27, and closely fitted for lengthwise reciprocation in a bore 28, within a block 29, ordinarily secured in convenient position on a fixed part of the press. A port 30, intermediate the ends of the bore 28, communicates with the pump discharge pipe 22. Ports 31 and 32 adjacent the ends of the bore 28, communicate through a passage 33 with the pump return pipe 21. Ports 34 and 35, intermediate the ports 31, 30, and 32, are connected with pipes 17 and 18, respectively. The valve is controlled by an appropriate hand lever 36 connected thereto through a stem 37.

With the valve in the intermediate position shown in Figure 1, ports 31, 30, and 32 are blocked by the piston heads 23, 24 and 25, respectively, so that there is no flow through the valve and the piston 16 is at rest. When the valve is shifted toward the right into the full line position of Figure 2, communication is established between ports 30 and 34, and between ports 32 and 35, so that liquid discharged by the pump through pipe 22 passes through pipe 17 into the upper end of cylinder 15, and the piston 16 moves down, liquid from the lower end of the cylinder 16 escaping through pipe 18, passage 33 and pipe 21 back to the pump. When the valve isshifted toward the left into the dotted line position of Figure 2, communicatlon 1s established between ports 30 and 35 and between ports 34 and 31, so that liquid discharged by the pump is delivered through pipes 22 and 18 to the lower end of cylinder 15, raising the piston 16, liquid from the upper end of the cylinder escaping through p1pes 17 and 21 back to the'pump.

The ram 13 moves with the piston 16 toward and from the work, provision being made-for maintaining the power cylinder 10 flooded with liquid during such movement. Liquid for this purpose is supplied from an appropriate reservoir, preferably disposed above the power cylinder so that liquid may flow by gravity from the reservoir to the cylinder. In the press shown thereservoir is in the form of a tank 38, mounted on the top of the 'power cylinder and surrounding the auxiliary cylinder 15. A pipe 39 leading from the bottom of this tank normally communicates, through an appropriate valve 40, with a' passage 41 leading into the power cylinder. An overflow pipe 42, leading from the top of the tank, permits the discharge of excess liquid therefrom to an appropriate sump, preferably in the base of the pump.

The valve 40 is adjustable to block communication between the tank 38 and the power cylinder and to open communication between the power cylinder and the pipe 17, to thereby expose the ram 13 to the pressure in the main circuit. In this instance this valve comprises a piston having two heads 43 and 44 connected by a reduced portion 45, closely fitted for reciprocation in a bore 46 formed in a block 47, fixed to the power cylinder 10. The head 43 controls a port 48 in open communication with the pipe 39, and the head 44 controls a port 49 in open communication with a pipe 50 leading from the pipe 17. An intermediate annular chamber 51 surrounding the bore 46 maintains communication between the bore and the passage 41. The arrangement. is such that with the valve 40 in the upper position of Figure 1, port 49 is blocked by head 44, and port 48 is uncovered, so that liquid is free to flow between the power cylinder and the tank 38. WVith the valve 40 in the lower position of Figure 3 port. 48 is blocked by head 43 and port 49 is uncovered, so that the power cylinder is then open to the pipe 17 through passage 41 and pipe 50.

The valve 40 normally assumes the upper position of Figure 1, any appropriate means, such as a light spring 51 being provided for yieldably maintaining the valve in this position. The valve is actuated by a piston 52 fixed to the stem 53 thereof, and reciproca le in a small cylinder 54, fixed to the block 46. A pipe 55 leading from the bottom of the cylinder 54 communicates with pipe 18,

mousse and apipe 56 leading from the top of the cylinder 54, communicates, through a twoway check ,valve'57, with the pipe 50.

wThe valve 57 is such. as to permit a free flow of liquid from pipe 56 to pipe 50, but to prevent flow in the'opposite direction until a predetermined pressure. has been established within the pipe 50. The valve shown'.

comprises a housing. having a port 58 at one end in open communication with pipe 50, and a port 59 at the other end in open communication with pipe 56. A hollow valve element 60 .is yieldably retained upon its seat 61 by a spring 62. A ball check valve 63 within the element 60 permits an easy flow of liquid from pipe 56 upwardly through the valve. Downward flow through the valve into pipe 56 is prevented, however, until the pressure within pipe 50 is sufiicient to force the hollow element 60 from its seat, against the pressure of the spring 61.

A description of a complete operating cycle will now be given. To start the press the operator swings the hand lever 36 toward the right so as to shift the valve 19 into the full line position ofFigure 2. Liquid discharged by the pump into pipe 22 then flows upwardly through pipe 17 into the upper end of'the auxiliary cylinder 15, and the piston 16 and ram 13 move down toward the work at a rate determined by the displacement of the pump.

This movement is much more rapid than if the pump were delivering into the power cylinder 10, because the auxiliary cylinder is so much smaller than the power cylinder, and

consequently demands less volume from the pump; During this descent of the ram the valve 40 is in the upper position of Figure 1, and liquid from the tank 38 fiows by gravity into the power cylinder to maintain the same in a flooded condition. This descent continues until the ram 13 is arrested by engagement with the work. The resistance offered by the work to further advance of the ram results I pressure of the ram in addition to the pressure exerted by the auxiliary piston 16. The operator then swings the hand lever 36 toward the left, so as to shift the valve 19 into the left extreme position, indicated in dotted lines in Figure 2. Pipe 17 is thus opened to the return pipe 21 leading to the pump, and the pump discharge pipe 22 is connected through pipe 18 to the lower end of the auxiliary cylinder 15, causing the auxiliary cylinder 16 and ram 13 to rise. The working pressure thus established in pipe 18 is transmitted and cylinder,

through pipe to the bottom ofcylinder 54, causing the piston 52 to rise and thereby return the valve 40 to the upper position of Figure 1. Power cylinder 10 is again opened to the tank 38, so that during the upward movement of the ram 13, liquid from the cylinder 10 is free to return to the tank.

Various changes may be made in the embodiment of the invention hereinabove specifically described without departing from or sacrificing any of the advantages of the invention as dehned in the appended claims.

We claim 1. In a press the combination of a ram, a cooperating power cylinder, auxiliary hydraulically actuated means for operating said ram, a reversible flow hydrauliccircuit for operating said means in either direction, and means responsive to the pressure in said circuit for opening communication between said circuit and power cylinder.

2. In a press the combination of a ram, a cooperating power cylinder, auxiliary hydraulically operated means for operating said ram, a reversible flow hydraulic circuit for operating said means in either direction, a reservoir, and means controlled by the pressure in said circuit for opening said cylinder to said circuit or to said reservoir.

3. In a press the combination of a ram, 9. cooperating power cylinder, auxiliary hydraulically operated meansv for operating said ram, a reversible flow hydraulic circuit for operating said means in either direction, a reservoir, valve mechanism operable to open said power cylinder to said circuit or said reservoir, and means responsive to pressure within said circuit for operating said valve.

4. The combination with a large piston of a small piston and cylinder connected in driving relation therewith, a reversible flow hydraulic circuit for operating said small piston in either direction, and means responsive to the pressure in said circuit for connecting said circuit with said large cylinder.

5. The combination with a large piston and cylinder, of a small piston and cylinder connected in driving relation therewith, a reversible flow hydraulic circuit for operating said small piston in either direction, a reservoir, and means responsive to the pressure in said circuit for connecting said large cylinder with said circuit or with said reservoir.

6. The combination with a power cylinder and cooperating ram, of auxiliary hydraulically actuated means for operating said ram, a reversible flow hydraulic circuit for operating said means in either direction, valve mechanism controlling communication between said circuit and said power cylinder, and fluid actuated means responsive to the difference in pressure between the opposite sides of said circuit for operating said valve.

7. The combination with a power cylinder and cooperating ram, of an auxiliary hydraulically actuated means for operating said arm, a pump for delivering a driving liquid to said means to operate the same in either direction, and means responsive to the pressure in said driving liquid for admitting said driving liquid to said power cylinder.

8. The combination with a power cylinder and cooperating ram, of a pump, a reservoir, auxiliary hydraulic means actuated from said pump for operating said ram in either direction, valve mechanism adjustable to connect said cylinder with said pump or said reservoir, and fluid actuated means responsive to the working pressures in said auxiliary means for adjusting said valve mechanism.

9. The combination with a power cylinder and cooperating ram, of auxiliary means for operating said ram, a pump, a hydraulic connection between said pump for operating said means, a branch connection from said connection to said power cylinder, a valve in said branch connection, and fluid actuated means responsive to the pressure in said connections for adjusting said valve.

10. The combination with a power cylinder and cooperating ram, of auxiliary means for operating said ram, a pump, a hydraulic connection between said pump and said means to operate the same, a branch connection communicating with said hydraulic connection, a reservoir, valve mechanism adjustable to effect communication between said cylinder and said branch connection or said reservoir, and fluid actuated means responsive to the pressure in said connections for adjusting said valve.

In witness whereof, we hereunto subscribe our names this 29th day of December, 1925.

JOHN P. FERRIS. LAWRENCE A. BARRETT.

and said means 

